The Challenges of DNA Extraction in Different Assorted Food Matrices: A Review.

High-quality DNA extracts are imperative for downstream applications in molecular identification. Most processed food products undergo heat treatments causing DNA degradation, which hampers application of DNA-based techniques for food authentication. Moreover, the presence of inhibitors in processed food products is also problematic, as inhibitors can impede the process of obtaining high qualities and quantities of DNA. Various approaches in DNA extraction and factors in structure and texture of various food matrices affecting DNA extraction are explained in this review.

A higher sensitivity and efficiency of common primer multiplex PCR assay in identification of meat origin using NADH dehydrogenase subunit 4 gene.

A Common Primer Multiplex PCR (CP-M-PCR) was developed to detect meat origin of four groups of animal (pig, ruminant, avian and rabbit). This method demonstrated higher sensitivity and efficiency than the conventional multiplex PCR. In this approach, a common forward primer was designed in the 5' end of a homologous region of mitochondrial NADH dehyrogenase subunit 4 (Nad 4) gene sequences of all the animal groups. Specific adapter reverse primers were designed by adding an adapter sequence at the 5' end. The same adapter sequence was used as the common adapter reverse primer. The primers generated specific fragments of 267, 370, 504, and 548 bp lengths for pig, ruminant, avian and rabbit meats, respectively. The use of adapter sequence at the 5' end of the common adapter reverse primers increased the efficiency of the amplification and the application of a common forward primer solved the complexity in multiplex PCR system. Bands of specific amplification can be detected in the PCR assays containing as low as 10(-6) µM of adapter reverse primer. This result indicated that the sensitivity was tremendously increased as compared to the conventional multiplex PCR (10(-3) µM). CP-M-PCR detection limit of the DNA samples was 0.1 ng for the four groups of meats. CP-M-PCR has greatly improved the sensitivity and efficiency of the PCR system for a more reliable and accurate outcome than conventional multiplex PCR system.

Polymerase chain reaction assay targeting cytochrome b gene for the detection of dog meat adulteration in meatball formulation.

A polymerase chain reaction (PCR) assay for the assessment of dog meat adulteration in meatballs was developed. The assay selectively amplified a 100-bp region of canine mitochondrial cytochrome b gene from pure, raw, processed and mixed backgrounds. The specificity of the assay was tested against 11 animals and 3 plants species, commonly available for meatball formulation. The stability of the assay was proven under extensively autoclaving conditions that breakdown target DNA. A blind test from ready to eat chicken and beef meatballs showed that the assay can repeatedly detect 0.2% canine meat tissues under complex matrices using 0.04 ng of dog DNA extracted from differentially treated meatballs. The simplicity, stability and sensitivity of the assay suggested that it could be used in halal food industry for the authentication of canine derivatives in processed foods.